Clonazepam has an elimination half-life of 18 – 50 hours to 19 – 60 hours, and is generally considered to be a long-acting benzodiazepine. Clonazepam has an intermediate onset of action, with a peak blood level occurring one to four hours after oral administration.

It's worth noting that the sudden discontinuation of benzodiazepines can be potentially life-threatening for individuals using regularly for extended periods of time.[4] It is highly recommended to taper one's dose by gradually lowering the amount taken each day for a prolonged period of time instead of stopping abruptly.[5]

Chemistry

Clonazepam is a drug of the benzodiazepine class. Benzodiazepine drugs contain a benzene ring fused to a diazepine ring, which is a seven membered ring with the two nitrogen constituents located at R1 and R4. The benzyl ring of clonazepam is substituted at R8 with a nitro group, NO2-. Further, the diazepine ring is bonded at R5 to a 2-chlorinated phenyl ring. Clonazepam also contains an oxygen group double bonded to R2 of its diazepine ring to form a ketone. This oxygen substitution at R2 is shared with other benzodiazepine drugs with the suffix -azepam.

Pharmacology

Benzodiazepines produce a variety of effects by binding to the benzodiazepine receptor site and magnifying the efficiency and effects of the neurotransmitter gamma aminobutyric acid (GABA) by acting on its receptors.[6] As this site is the most prolific inhibitory receptor set within the brain, its modulation results in the sedating (or calming effects) of clonazepam on the nervous system.

The anticonvulsant properties of benzodiazepines may be, in part or entirely, due to binding to voltage-dependent sodium channels rather than benzodiazepine receptors.[7]

Subjective effects

The effects listed below are based upon the subjective effects index and personal experiences of PsychonautWikicontributors. These effects should be taken with a grain of salt and will rarely (if ever) occur all at once, but heavier doses will increase the chances of inducing a full range of effects. Likewise, adverse effects become much more likely on higher doses and may include serious injury or death.

Physical effects

Sedation - In terms of energy level alterations, this drug has the potential to be extremely sedating and often results in an overwhelmingly lethargic state. At higher levels, this causes users to suddenly feel as if they are extremely sleep deprived and have not slept for days, forcing them to sit down and generally feel as if they are constantly on the verge of passing out instead of engaging in physical activities. This sense of sleep deprivation increases proportional to dosage and eventually becomes powerful enough to force a person into complete unconsciousness.

Physical euphoria - Clonazepam is similar to alprazolam, where despite suppressing emotion, people report moderate-strong feelings of relaxation, pleasure and comfort in the body. This seems to present itself more often in those with pre-existing anxiety However, this isn't consistent with everyone, with some users reporting no euphoric qualities at all.

Visual effects

Paradoxical effects

Paradoxical reactions to benzodiazepines such as increased seizures (in epileptics), aggression, increased anxiety, violent behavior, loss of impulse control, irritability and suicidal behavior sometimes occur (although they are rare in the general population, with an incidence rate below 1%).[8][9]
These paradoxical effects occur with greater frequency in recreational abusers, individuals with mental disorders, children, and patients on high-dosage regimes.[10][11]

Cognitive effects

The cognitive effects of clonazepam can be broken down into several components which progressively intensify proportional to dosage. The general head space of clonazepam is described by many as one of intense relaxation, anxiety suppression and decreased inhibition. It contains a large number of typical depressants cognitive effects.
The most prominent of these cognitive effects generally include:

Delusions of sobriety - This is the false belief that one is perfectly sober despite obvious evidence to the contrary such as severe cognitive impairment and an inability to fully communicate with others. It most commonly occurs at heavy dosages.

After effects

Rebound anxiety - Rebound anxiety is a commonly observed effect with anxiety relieving substances like benzodiazepines. It typically corresponds to the total duration spent under the substance's influence along with the total amount consumed in a given period, an effect which can easily lend itself to cycles of dependence and addiction.

Residual sleepiness - While benzodiazepines can be used as an effective sleep-inducing aid, their effects may persist into the morning afterward, which may lead users to feeling "groggy" or "dull" for up to a few hours.

Tolerance and addiction potential

Clonazepam is extremely physically and psychologically addictive.

Tolerance will develop to the sedative-hypnotic effects within a couple of days of continuous use. After cessation, the tolerance returns to baseline in 7 - 14 days. However, in certain cases this may take significantly longer in a manner which is proportional to the duration and intensity of one's long-term usage.

Withdrawal symptoms or rebound symptoms may occur after ceasing usage abruptly following a few weeks or longer of steady dosing, and may necessitate a gradual dose reduction. For more information on tapering from benzodiazepines in a controlled manner, please see this guide.

Benzodiazepine discontinuation is notoriously difficult; it is potentially life-threatening for individuals using regularly to discontinue use without tapering their dose over a period of weeks. There is an increased risk of hypertension, seizures, and death.[15] Drugs which lower the seizure threshold such as tramadol should be avoided during withdrawal.

Clonazopam presents cross-tolerance with all benzodiazepines, meaning that after its consumption all benzodiazepines will have a reduced effect.

Overdose

Benzodiazepine overdose may occur when a benzodiazepine is taken in extremely heavy quantities or concurrently with other depressants. This is particularly dangerous with other GABAergic depressants such as barbiturates and alcohol since they work in a similar fashion, but bind to distinct allosteric sites on the GABAA receptor, thus their effects potentiate one another. Benzodiazepines increase the frequency in which the chlorine ion pore opens on the GABAA receptor while barbiturates increase the duration in which they are open, meaning when both are consumed, the ion pore will open more frequently and stay open longer[16]. Benzodiazepine overdose is a medical emergency that may lead to a coma, permanent brain injury or death if not treated promptly and properly.

Dangerous interactions

Although many psychoactive substances are reasonably safe to use on their own, they can quickly become harmful and even life-threatening when taken with other substances. The following section lists some known dangerous combinations, but it may not include all of them. Furthermore, a combination that seems to be harmless in low doses can still greatly increase the risk of injury or death when the doses are slightly increased. Independent research should always be conducted to ensure that a combination of two or more substances is safe to consume. Some interactions listed have been sourced from Tripsit.

Stimulants - It can be dangerous to combine depressants with stimulants due to the risk of accidental excessive intoxication. Stimulants mask the sedative effect of depressants, which is the main factor most people use to gauge their level of intoxication. Once the stimulant effects wear off, the effects of the depressant will significantly increase, leading to intensified disinhibition, motor control loss, and dangerous black-out states. This combination can also potentially result in severe dehydration if one's fluid intake is not closely monitored. If choosing to combine these substances, one should strictly limit themselves to a pre-set schedule of dosing only a certain amount per hour until a maximum threshold has been reached.